Damage to semiconductor devices from electrostatic discharge (ESD) can occur at any point, from manufacture to field service. An electrostatic discharge is defined as a transfer of charge between bodies at different electrical potentials. When subject to high discharge voltages, many semiconductor devices can suffer permanent effects. For instance, an electrostatic discharge event may cause a catastrophic failure or a latent defect in a device. A catastrophic failure occurs when the semiconductor device no longer functions after the electrostatic discharge event, while a latent defect is more difficult to identify. In the case of a latent defect, the semiconductor device may be partially degraded due to the electrostatic discharge event, but still continue to perform its intended function. The degradation, however, may reduce the operating life of the device, potentially resulting in costly future repair or replacement operations.
Various external solutions and procedures have been developed for preventing or reducing electrostatic discharge damage during device fabrication. Manufacturers often implement electrostatic-protective areas (EPAs), with international standards existing that define a typical EPA. For instance, EPA standards are provided by the International Electrochemical Commission (IEC), and by the American National Standards Institute (ANSI).
In addition to external electrostatic discharge prevention mechanisms, semiconductor devices may also incorporate electrostatic discharge protection internally into the design or layout of the device. For instance, various methods and configurations for adding an N+ or P+ doped region have been implemented in field-effect transistor (FET) devices in association with the source/drain (S/D) or gate regions. Additional enhancements to these internal electrostatic discharge protection designs are desired to provide electrostatic discharge protection for, for instance, high-voltage applications, at low fabrication cost.